Quantum Gravity Effects in Black Holes and Gravitational Waves

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Quantum-gravity effects as noise for
gravity-wave detectors

I discuss a mechanism that can allow Planck scale effects to manifest themselves as a source of lof-frequency noise for interferometers.  The mechanism requires a discrete formulation of dynamics at the Planck scale.

Dancing in the Dark: Images of Quantum Black Holes

There have recently been a number of rather surprising suggestions
that the quantum nature of black holes is manifested on macroscopic
scales.  This raises the question of just what the image of such an
object should look like.  The answer is more than simply academic; with
the advent of the Event Horizon Telescope (EHT), a millimetre-wave very
long baseline array, it is now possible to probe a handful of
supermassive black holes with angular resolutions sufficient to image
their horizons.  I will discuss what we might expect to see, and how in
the near future we will begin to empirically probe the existence of
black hole quantum states with horizon scale curvature deviations from
general relativity.


The Irritating Persistence of Horizons
In some approaches to quantum gravity Lorentz invariance is
modified. Without Lorentz invariance one can theoretically see behind
the usual Killing horizon of a black hole if, for example, one allowed
for superluminal propagation. This in turn raises the possibility that
one could in principle probe the singularity and the quantum gravity
regime. We discuss how Lorentz violating black hole solutions in
Einstein-aether theory unfortunately possess another causal boundary
behind the Killing horizon that is impenetrable to any superluminal
mode. We also detail progress in determining the laws of black hole
mechanics and the radiation spectrum from these so-called "universal
horizons". Our results suggest that even if superluminal dispersion at
high frequencies did exist in nature, singularities and their associated
quantum gravity resolutions may very well remain locked behind